Residual stresses can have substantial and detrimental influences on the integrity of power plant infrastructure. In this work, we aim to characterise the development and evolution of residual stresses in a low-alloy reactor pressure vessel steel that has been clad with a nickel-based weld overlay material such as Inconel alloy 690, by making measurements in samples in the as-welded condition and after post-weld heat treatment. In doing so, we hope to improve the level of understanding we have of the development and relaxation of residual stress within and adjacent to the clad layer, i.e. near to the interface between two dissimilar materials. This work is of importance to the power industry (and nuclear industry in particular). It is hoped that the work will be of vital importance in validating numerical models and improving our understanding of material behavior.